1. Technical Field
The present disclosure relates to graphic processing, and more particularly to an image decoding method and apparatus.
2. Description of Related Art
FIG. 1 is a schematic view of a commonly used image decoding flow for a joint photographic experts group (JPEG) decoder.
As illustrated, a JPEG decoder 10 comprises an entropy decoder 120, a dequantizer 130 and an inverse discrete cosine transformer (IDCT) 140. It should be noted that the JPEG decoder 10 is a discrete cosine transform-based (DCT-based) decoder and JPEG image data is composed of multiple 8×8 pixel arrays.
Input image data 110 is a compressed M×N pixel matrix. When a JPEG image decoding operation is performed, the entropy decoder 120 receives and processes the input image data 110 as two-dimensional (2D) image data (not shown) according to table specification 115. The dequantizer 130 performs a dequantizing operation on the input image data 110 according to a second table specification 125, performing a scalar multiplication on each pixel array involved in a M×N pixel matrix forming the input image data 110.
The inverse discrete cosine transformer 140 performs an IDCT operation on the dequantized input image data. A color space converter 150 performs a color space conversion on the IDCT input image data, and the input image data 110 is correspondingly converted to output image data 160 in RGB format.
When the JPEG decoder 10 is implemented by software modules, a JPEG image decoding module, for example, hardware components in the JPEG image decoding module, are also implemented by software modules and embedded in a central processing unit (CPU). As a result, the CPU may provide a JPEG image processing function via those software modules and implement the described JPEG image decoding flow using the JPEG image decoding module. However, performance of the JPEG image decoding module may be limited by the operational capacity of the CPU.